Detection Machine

Abstract

To provide a detector which is equipped with a condenser lens and is able to detect a laser beam coming from a position away from the front of the detector.SOLUTION: In a detector 1, a photodetector 42 receives a laser beam through a condenser lens 41, and an alert section 6 reports prescribed information based on the detection of the laser beam by the photodetector 42. The condenser lens 41 has a flat region 412 and a Fresnel lens region 411. Both sides of the flat region where the laser beam enters are flat. The Fresnel lens region is uneven on both sides or one side where the laser beam enters.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a detector capable of receiving laser light emitted by a laser type speed measurement device. [Background technology]

[0002] When a vehicle approaches a speed measuring device or receives radar waves from the speed measuring device, the detector issues information directly or indirectly encouraging compliance with the speed limit. This detector does this by receiving radar waves emitted from the speed measuring device with an antenna. The detector also has a function of notifying a warning when it detects that the vehicle's position, determined by GPS, has come within a certain distance from the position of a previously registered speed measuring device.

[0003] In recent years, speed measuring devices have been moving towards non-radar types, such as loop coil types and photocell types. In line with this trend towards non-radar, laser light type speed measuring devices have been developed. Laser light type speed measuring devices detect the speed of a vehicle by scanning a specific area with a laser light, irradiating the vehicle with the laser light and detecting the reflected laser light. There are fixed types that are installed in a fixed location and mobile types that are easy to install and remove.

[0004] In response to the speed detection method using laser light, recent detectors are equipped with a light receiving element such as a photodiode. A condenser lens such as a Fresnel lens is installed in front of the light receiving element to ensure a large effective light receiving area and guide a large amount of light to the light receiving element (see, for example, Patent Document 1). Patent Document 1 proposes that the light receiving element be placed in front of the focal length because the light around the condenser lens tends to gather at the center of the optical axis in front of the focal length. In other words, it proposes that the light receiving element be placed at a position that is closer to the focal length by the spherical aberration of the condenser lens. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-193966 A Summary of the Invention [Problem to be solved by the invention]

[0006] 10 shows the optical path when the condenser lens 100 is placed, (a) shows the case where the laser light is irradiated from the front, and (b) shows the case where the laser light is irradiated from a position tilted 30° from the front. The entire surface of this condenser lens 100 is a Fresnel lens.

[0007] As shown in (a) of Fig. 10, when a speed measuring device is located in front of a detector, if the detector is equipped with a full-surface Fresnel lens condenser lens 100, the condenser lens 100 condenses light over a wider range than the element size of the light receiving element 42 toward the light receiving element 42. In other words, when the detector is equipped with the condenser lens 100, even if the laser light is diffused or the optical axis of the laser light does not precisely match the light receiving element 42, the possibility of detecting the laser light increases. Therefore, even if the speed measuring device is located far away, information that directly or indirectly urges compliance with the speed limit can be notified.

[0008] On the other hand, as shown in (b) of Fig. 10, if the speed measuring device is located away from the front of the detector, the laser light enters the condenser lens 100 at an angle, and the light transmitted through the condenser lens 100 forms a focal point F at a position away from the axis A of the condenser lens 100. Therefore, if the element size of the light receiving element 42 is small, most of the light transmitted through the condenser lens 100 will miss the light receiving element 42. Therefore, the presence of the condenser lens 100 rather narrows the effective light receiving area, making it difficult for the light receiving element 42 to detect the laser light.

[0009] Furthermore, if the focusing lens 100 is a full Fresnel lens, the light rays that barely reach the light receiving element 42 on their way to the focal point F are attenuated because a portion of them travels in a direction different from that of the light receiving element 42 as scattered rays Ls due to the rise surface of the outer periphery of the Fresnel lens.

[0010] The present invention has been proposed to solve the problems of the conventional technology as described above, and its object is to provide a detector that is equipped with a focusing lens and can easily detect laser light arriving from a position away from the front of the detector. [Means for solving the problem]

[0011] In order to achieve the above-mentioned object, the detector of the present invention is a detector installed in a vehicle and comprises a focusing lens into which laser light emitted by a speed measuring device is incident, a light receiving element which receives the laser light through the focusing lens, and an alarm unit which notifies predetermined information in response to reception of light by the light receiving element, characterized in that the focusing lens has a flat area which is flat on both sides into which the laser light is incident, and a Fresnel lens area which has unevenness on both sides or one side into which the laser light is incident.

[0012] The Fresnel lens area may extend concentrically from the center of the collecting lens, and one or both areas horizontally adjacent to a central area of ​​the Fresnel lens area may be missing from an outer circumferential area of ​​the Fresnel lens area, and the flat area may be formed in the missing area of ​​the Fresnel lens area.

[0013] The flat region may be located at the center of the condenser lens, and the Fresnel lens region may extend concentrically with the center of the condenser lens and be formed in an annular shape around the flat region.

[0014] The light receiving element may be disposed at a position closer to the condenser lens than a position closer to the focal length by the spherical aberration. Effect of the Invention

[0015] According to the present invention, even if a focusing lens is provided, it is possible to improve the detection capability of laser light arriving from a position away from the front of the detector. [Brief description of the drawings]

[0016] [Figure 1] 1 is a perspective view showing the surface of the detector facing outside the vehicle. [Diagram 2] FIG. 2 is a perspective view showing the surface of the detector facing the interior of the vehicle. [Diagram 3] FIG. 2 is a block diagram showing the internal configuration of the detector. [Figure 4] 2 is a block diagram showing the configuration of a control unit of the detector. FIG. [Diagram 5] FIG. 2 is a schematic diagram showing a first example of a condenser lens. [Figure 6] 1A and 1B are schematic diagrams showing the optical path of laser light passing through the focusing lens of the first example, where (a) shows the case where the laser light arrives from the front, and (b) shows the case where the laser light arrives from a position 30° away from the front. [Figure 7] 11 is a schematic diagram showing another example of the positional relationship between the condenser lens and the light receiving element. FIG. [Figure 8] FIG. 13 is a schematic diagram showing a second example of a condenser lens. [Figure 9] 5A and 5B are schematic diagrams showing the optical path of laser light passing through the focusing lens of the second example, where (a) shows the case where the laser light arrives from the front, and (b) shows the case where the laser light arrives from a position 30° away from the front. [Figure 10] The optical path when the entire surface is a Fresnel lens is shown, where (a) is the case when the light is irradiated from the front of the lens, and (b) is the case when the light is irradiated from a position tilted 30° from the front. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] (Overall composition) A detector according to an embodiment of the present invention will be described in detail with reference to the drawings. FIGS. 1 and 2 are perspective views showing a detector 1. The detector 1 is installed in a vehicle such as an automobile, a motorcycle, a truck, or a bus. The detector 1 notifies the driver of information encouraging the driver to observe the speed limit by direct or indirect content when an event that should encourage the driver to observe the speed limit occurs. The detector 1 is typically installed on the dashboard and is powered from the vehicle side via an OBD-II connector or a cigarette lighter socket. The dashboard is an example of a place that is easy to receive radar waves and laser light emitted by a speed measurement device and can notify the driver of information. Radar waves and laser light are collectively called electromagnetic waves.

[0018] Speed ​​measuring devices include radar types that emit radar waves, non-radar types that have loop coils or photocells, and laser light types that emit laser light, and the radar and laser light types are available in both fixed and mobile types. Events that should encourage speeding are when a vehicle arrives within a specified distance of a speed measuring device whose installation location is known, and when electromagnetic waves emitted by the speed measuring device are received. Examples of information to be notified include the presence of the speed measuring device, the type of the speed measuring device, the reception and type of electromagnetic waves emitted by the speed measuring device, or a warning to observe the speed limit, or a combination of these.

[0019] The detector 1 is equipped with a screen 14, a speaker 15, and a lamp 16 on the outer surface of a housing 10. The screen 14 is a liquid crystal display or an organic EL display, etc., and is arranged on the front 12 of the detector 1, and displays the alarm information in a visually appealing format such as letters, pictures, and symbols. The speaker 15 outputs the alarm information as audio. The lamp 16 notifies the alarm information by regular emission of light such as colors, flashing, and lighting intervals. The front 12 faces the interior of the vehicle and is visible to the driver, while the back 11 faces the outside of the vehicle via the windshield.

[0020] The back surface 11 of the detector 1 is a receiving area 13. In this receiving area 13, a radio wave sensor 2, a positioning signal receiving unit 3, and an optical sensor 4 are arranged so as to be housed inside a housing 10. The radio wave sensor 2 has an antenna and a receiver such as a superheterodyne type, and receives and detects radar waves in the wavelength bands of X-band and K-band emitted by a radar-type speed measuring device. When the radio wave sensor 2 receives the radar waves from the speed measuring device, it outputs a detection signal. The positioning signal receiving unit 3 has an antenna, demodulator, and processor capable of receiving radio signals from a positioning satellite, receives and demodulates the positioning signal of a GNSS (Global Navigation Satellite System), and calculates the vehicle's position consisting of the latitude and longitude of the current position.

[0021] Fig. 3 is a block diagram showing the internal configuration of the detector 1. As shown in Fig. 3, the optical sensor 4 includes a condenser lens 41, a light receiving element 42, and a conversion unit 43, and outputs a detection signal when it receives light. The detection signal is a voltage signal having a pulse width that matches the light receiving time, and is output at pulse intervals that match the light receiving interval.

[0022] The condenser lens 41 transmits the laser light emitted by the speed measurement device toward the light receiving element 42. The condenser lens 41 is preferably made of a material that easily transmits light even from an oblique angle, for example, acrylic resin. This makes it possible to prevent reception leakage even when the condenser lens 41 is obliquely intersecting the optical axis of the laser light emitted by the speed measurement device due to the speed measurement device being installed along a road. However, the condenser lens 41 is not limited to being made of acrylic resin, and a wide variety of well-known materials can be used.

[0023] Furthermore, by selecting a material, the condenser lens 41 may have a function of a filter that transmits a wavelength band including the wavelength of the laser light emitted by the speed measurement device. This wavelength band may include, for example, the wavelengths of light emitted by VICS (registered trademark), N system, an in-vehicle distance measurement sensor, other facilities on the road, and vehicles in motion. For example, the wavelength band transmitted by the condenser lens 41 may include light emitted by an electronic scoreboard mounted on the vehicle. Alternatively, a filter that transmits a wavelength band including the wavelength of the laser light emitted by the speed measurement device may be separately disposed.

[0024] The light receiving element 42 is a detector that receives the laser light via the condenser lens 41 and passes a current in response to the received light. The light receiving element 42 is disposed behind the condenser lens 41 and receives the light that has passed through the condenser lens 41. The light receiving element 42 is, for example, a phototransistor or a photodiode. The conversion unit 43 is configured to include, for example, an operational amplifier, and converts the current signal output by the light receiving element 42 into a voltage signal and outputs it as a detection signal.

[0025] 3, the detector 1 further includes a control unit 5 and an alarm unit 6. The radio wave sensor 2, the positioning signal receiving unit 3, and the optical sensor 4 input signals to the control unit 5. This control unit 5 is a so-called computer that includes a processor such as a CPU, FPGA, or microcomputer, storage for storing programs and data, and a work memory.

[0026] The control unit 5 determines whether the radio wave sensor 2 and the optical sensor 4 have received electromagnetic waves from a speed measuring device. The control unit 5 also determines the distance between the vehicle position output by the positioning signal receiving unit 3 and a speed measuring device whose installation location is known, and a location where a speed measuring device has been installed in the past (hereinafter collectively referred to as a registered speed measuring device). Then, the control unit 5 causes the notification unit 6 to notify information according to the determination result. The notification unit 6 is a screen 14, a speaker 15, a lamp 16, or a combination of these, which are arranged on the outer surface of the housing 10.

[0027] 4, the control unit 5 includes a radar wave processing unit 51, a distance calculation unit 52, a storage unit 53, and a laser light determination unit 54, which are implemented by program processing by a processor, etc. When a detection signal from the radio wave sensor 2 is input to the control unit 5, the radar wave processing unit 51 performs interrupt processing and causes the notification unit 6 to notify information encouraging compliance with the speed limit. In particular, it is desirable for the radar wave processing unit 51 to notify the notification unit 6 of information notifying the presence of a radar-type speed measurement device and the reception of radar waves emitted by the speed measurement device.

[0028] The memory unit 53 is configured with a storage provided in the detector 1 or a portable storage medium such as an SD card, and stores the latitude and longitude of the registered speed measurement device. The distance calculation unit 52 calculates the distance between the vehicle position output by the positioning signal receiving unit 3 and the registered speed measurement device stored in the memory unit 53.

[0029] Furthermore, the distance calculation unit 52 has a preset threshold value and compares the calculation result with the threshold value. If the calculation result is equal to or less than the threshold value, that is, if the vehicle position is within a predetermined distance from a registered speed measurement device, the distance calculation unit 52 controls the notification unit 6 to notify the information. In particular, it is desirable for the distance calculation unit 52 to cause the notification unit 6 to notify the presence and type of a registered speed measurement device, as well as information notifying the distance between the registered speed measurement device and the vehicle position.

[0030] When a detection signal from the optical sensor 4 is input to the control unit 5, the laser light determination unit 54 performs interrupt processing and determines whether the optical sensor 4 has received laser light from a speed measuring device. This laser light determination unit 54 determines whether the light reception interval and light reception time match the laser light scanning method of the speed measuring device, and when it determines that laser light has been received, it controls the notification unit 6 to notify information. In particular, it is desirable for the laser light determination unit 54 to cause the notification unit 6 to notify information notifying the presence of a laser type speed measuring device and the reception of laser light irradiated by the speed measuring device.

[0031] (First example of an optical system) Fig. 5 is a schematic diagram showing a first example of condenser lens 41 provided in such detector 1, and is a cross-sectional view taken along the surface of condenser lens 41. The left-right direction in Fig. 5 corresponds to the horizontal direction when detector 1 is installed on a horizontal surface. As shown in Fig. 5, condenser lens 41 has a mixture of Fresnel lens region 411 and flat region 412 within the region where laser light is incident.

[0032] The Fresnel lens region 411 is a region in which the curved surface of the lens is divided into concentric circles and arranged on the same plane, and spreads out concentrically from the center of the condenser lens 41. The central axis of the Fresnel lens region 411 passes through the center of the light receiving surface of the light receiving element 42. The Fresnel lens region 411 has unevenness consisting of a Fresnel surface corresponding to the curved surface of the lens and a rise surface which is a step between the Fresnel surfaces. The unevenness is formed on the surface of the condenser lens 41 facing the light receiving element 42, and the opposite surface is a flat surface. However, if the light incident from the surface opposite to the surface facing the light receiving element 42 can be collected on the light receiving element 42 side, the Fresnel surface and the rise surface may also be arranged on the surface opposite to the surface facing the light receiving element 42 so as to spread out concentrically from the center of the condenser lens 41.

[0033] The flat region 412 is a region having flat surfaces on both sides of the condenser lens 41. The Fresnel lens region 411 refracts and condenses the laser light toward the focal point F, whereas the light passing through the flat region 412 does not change the angle of incidence and the angle of emission to the condenser lens 41. The flat region 412 is formed so as to lack one or both regions horizontally adjacent to the central region 411a of the Fresnel lens region 411 in the outer peripheral region 411b of the Fresnel lens region 411. When the speed measuring device is installed only above the road and on the side of the road, the flat region 412 may be formed only in the region horizontally adjacent to the central region 411a of the Fresnel lens region 411 on the side of the road.

[0034] The total height of the flat region 412 coincides with the height of the light receiving element 42, the bottom side of the flat region 412 coincides with the bottom side of the light receiving element 42, and the top side of the flat region 412 coincides with the top side of the light receiving element 42. The flat region 412 extends to the side edge of the condensing lens 41. It is preferable that the inner side of the flat region 412 is positioned so that if an imaginary straight line is extended at an angle at which the light receiving sensitivity of the light receiving element 42 is desired to be increased, and the side extending up and down passes through the inner side of the flat region 412, i.e., the boundary with the central region 411a of the condensing lens 41, the imaginary straight line passes through one side of the light receiving element 42.

[0035] If the inner side edge of flat region 412 is located closer to the center of collecting lens 41 than the position on this virtual straight line, central region 411a of Fresnel lens region 411 becomes narrower, and when laser light arrives from the front, the amount of light received by light receiving element 42 decreases. If the inner side edge is located at this position, the amount of light received reaches a peak.

[0036] FIG. 6 is a schematic diagram showing the optical path of the laser light passing through this focusing lens 41, where (a) shows the case where the laser light arrives from the front, and (b) shows the case where the laser light arrives from a position 30° away from the front.

[0037] As shown in FIG. 6A, the flat region 412 of the condenser lens 41 transmits light without refracting it. Therefore, when the laser light enters the condenser lens 41 from the front and the light receiving element 42 is small, the light receiving element 42 cannot receive the light that passes through the flat region 412. However, the flat region 412 is a part of the outer peripheral region 411b, and the Fresnel lens region 411 covers most of the outer peripheral region 411b. In addition, the light that passes through the Fresnel lens region 411 forms a focus F on the light receiving element 42. The light receiving element 42 has high sensitivity to the condensed light. Therefore, the condenser lens 41 can guide the laser light approaching from the front to the light receiving element 42 with a sufficient amount of light, and the optical sensor 4 can output a detection signal.

[0038] 6(b), when the laser light arrives from a position away from the front, the light that has passed through the flat region 412 reaches the light receiving element 42 in a straight line in part or in whole, depending on the oblique angle between the laser light and the condenser lens 41. That is, the Fresnel lens region 411 guides the laser light arriving from a position away from the front to a focal point F that is located away from the light receiving element 42, but the light that has passed through the flat region 412 can enter the light receiving element 42 without being deviated toward the focal point F. Moreover, in the flat region 412 that has no rise surface, the generation of scattered rays Ls is small, and scattering of the light that passes through the flat region 412 is suppressed.

[0039] In this way, the optical sensor 4 having this focusing lens 41 improves its ability to receive laser light arriving from a position away from the front without significantly impairing its ability to receive laser light arriving from the front.

[0040] (Second example of an optical system) Fig. 7 is a schematic diagram showing another example of the positional relationship between the condenser lens 41 and the light receiving element 42. As shown in Fig. 7, the light receiving element 42 is positioned closer to the condenser lens 41 than the focal length of the condenser lens 41. Specifically, the light receiving element 42 approaches the condenser lens 41 from the focal length position, exceeding the spherical aberration of the condenser lens 41.

[0041] When the light receiving element 42 approaches the condenser lens 41 closer than the focal distance, a part of the light condensed at a focal point F that is off the axis A of the condenser lens 41 falls on the light receiving element 42. Therefore, with the addition of a part of the light that passes through the Fresnel lens region 411, the amount of laser light received that is incident from a position off the front can be increased.

[0042] Incidentally, when the imaginary straight line is extended to an angle at which it is desired to increase the light receiving sensitivity of the light receiving element 42 and passes through the outer side of the flat region 412, i.e., the side common to the edge of the condenser lens 41, it is preferable to move the light receiving element 42 closer to the condenser lens 41 until the imaginary straight line coincides with the end of the light receiving element 42. This makes it possible to prevent the light receiving element 42 from being brought too close to the condenser lens 41, causing light passing outside the flat region 412 to miss the side of the light receiving element 42.

[0043] (Third example of optical system) Fig. 8 is a schematic diagram showing a second example of collecting lens 41. As shown in Fig. 8, collecting lens 41 has a flat region 412 in a central region 411a within a Fresnel lens region 411. Fresnel lens region 411 extends only to an outer circumferential region 411b of collecting lens 41, and has a ring shape concentric with the center of collecting lens 41.

[0044] FIG. 9 is a schematic diagram showing the optical path of the laser light passing through the focusing lens 41 of the second example, where (a) shows the case where the laser light arrives from the front, and (b) shows the case where the laser light arrives from a position 30° away from the front.

[0045] 9A, the flat region 412 in the central region 411a of the condenser lens 41 emits light without refracting it. When viewed from the front, the light receiving element 42 is located behind the flat region 412. Therefore, all of the light that passes through the flat region 412 enters the light receiving element 42, although it is parallel light. The outer peripheral region 411b of the condenser lens 41 does not overlap with the light receiving element 42, but since it is the Fresnel lens region 411, the light that passes through the Fresnel lens region 411 is guided to the focal point F on the light receiving element 42 and is received by the light receiving element 42. Therefore, the condenser lens 41 can guide a sufficient amount of laser light approaching from the front to the light receiving element 42, and the optical sensor 4 can output a detection signal.

[0046] 9(b), when the laser light is irradiated from a position tilted from the front, a part of the light passing through the flat region 412 falls on the light receiving element 42 and can be received by the light receiving element 42. Since the flat region 412 does not have a rise surface, the light falling on the light receiving element 42 is less attenuated due to the generation of scattered rays Ls.

[0047] In this way, the optical sensor 4 having this focusing lens 41 also has improved ability to receive laser light arriving from a position away from the front without significantly impairing its ability to receive laser light arriving from the front.

[0048] Incidentally, even in the condenser lens 41 having the flat region 412 in the central region 411a, the light receiving element 42 may be disposed closer to the condenser lens 41 side than the focal position, thereby increasing the amount of received light.

[0049] (Action and effect) As described above, this detector is provided with the condenser lens 41 onto which the laser light emitted by the speed measuring device is incident, and the light receiving element 42 which receives the laser light via the condenser lens 41. The condenser lens 41 has a flat region 412 which is flat on both sides onto which the laser light is incident, and a Fresnel lens region 411 which has projections and recesses on both sides or one side onto which the laser light is incident.

[0050] As a result, the optical sensor 4 having this focusing lens 41 improves its ability to receive laser light arriving from a position away from the front without significantly impairing its ability to receive laser light arriving from the front.

[0051] As an example, Fresnel lens region 411 spreads out concentrically from the center of collecting lens 41, and in the outer circumferential region of Fresnel lens region 411, one or both regions horizontally adjacent to the central region of Fresnel lens region 411 are missing. Then, flat region 412 is formed in the missing region of Fresnel lens region 411.

[0052] This allows light that would otherwise be incident on the light receiving element 42 to pass through the flat region 412, improving the ability to receive laser light arriving from a position away from the front. In addition, since the flat region 412 is formed in a region limited to the area through which light that would otherwise be incident on the light receiving element 42 would pass, the ability to receive laser light arriving from the front is not significantly impaired.

[0053] As another example, flat region 412 is located at the center of condenser lens 41, and Fresnel lens region 412 spreads concentrically with the center of condenser lens 41 and is formed in a ring shape around the flat region. Even with this embodiment, light that is directly incident on light receiving element 42 unless refracted can pass through flat region 412, and the ability to receive laser light arriving from a position away from the front can be improved.

[0054] Furthermore, the light receiving element 42 is arranged to be placed at a position closer to the condenser lens 41 than the position closer by the spherical aberration from the focal length F. This allows most of the light passing through the Fresnel lens region 412 to be applied to the light receiving element 42, even if the focal point F is deviated from the axis A of the condenser lens 41, thereby improving the amount of light received.

[0055] (Other embodiments) Although the embodiment of the present invention has been described above, various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The embodiment and modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0056] 1 detector 10. Chassis 11 Back 12 Front 13 Reception area 14 screens 15 Speaker 16 Lamp 2. Radio wave sensor 3 Positioning signal receiver 4. Light Sensor 41 Condenser lens 411 Fresnel Lens Region 411a Central area 411b Outer area 411c Horizontal adjacent area 412 flat area 42 Photodetector 43 Conversion section 5. Control section 51 Radar wave processing section 52 Distance calculation unit 53 Memory section 54 Laser light judgment unit 6. Notification Department

Claims

1. A detector installed in a vehicle, a condenser lens into which the laser light emitted by the speed measuring device is incident; a light receiving element that receives the laser light through the condenser lens; a notification unit that notifies predetermined information in response to reception of light by the light receiving element; Equipped with The condenser lens is a flat region having flat surfaces on both sides into which the laser light is incident; a Fresnel lens region having irregularities on either or both sides onto which the laser light is incident; having the Fresnel lens region extends concentrically from the center of the condenser lens, and one or both regions adjacent to the central region of the Fresnel lens region in the horizontal direction are missing from the outer circumferential region of the Fresnel lens region, the flat region is formed in a region where the Fresnel lens region is missing; A detector characterized by:

2. the light receiving element is disposed at a position closer to the condenser lens than a position closer to the condenser lens by a spherical aberration; 2. The detector according to claim 1,

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